Home automation systems have been developing for many years. Conventional applications for such systems include control of lighting, heating ventilation air conditioning (HVAC), garden sprinklers, intelligent alarm systems etc. Wireless home automation systems have gained popularity in recent years due to the relative ease of installation in comparison to many hardwired systems. Many wireless home automation systems are aimed at do-it-yourself customers since such wireless devices need wiring for power. The most popular application for wireless home automation system is lighting control. Among lighting control devices, wall switch controlled lighting devices are the most popular. These switches are widely used in both residential and commercial buildings alike. A conventional method for converting a traditional wall switch to be controlled wirelessly requires a wall switch module. Such wall switch modules can replace existing wall switches.
For a conventional wall switch module, power may be supplied by existing wiring in an electrical switch box. Generally, only 2 wires are fed into an electrical switch box—a live feed from the AC power supply to the switch and a wire extending from the switch to the load. In most cases, the other side of the load is connected directly to the neutral of the AC power supply without returning to the switch box. FIG. 1 illustrates a circuit diagram of a typical wall switch 101. As shown in FIG. 1, switch 101 is connected to the live terminal 103 of an AC power supply, the other end of the switch 101 is connected to load 105, in this instance a light bulb. Neutral 107 is connected to the other side of load 105 and is not located inside the wall switch box. Most electrical systems include an earth ground connection 109 to the electrical switch box containing the switch 101, mainly for safety considerations and to satisfy electrical code requirements.
Conventionally, electrical switch boxes may be provided with only a live feed to supply the wall switch. Further, a neutral connection is not provided to complete the circuit with the electrical switch box. It may be very costly to run a neutral connection back to the electrical switch box when a neutral wire is not initially installed due to limited access to the existing wiring. Therefore, there is a need for a wall switch module that can operate using existing wiring in an electrical switch box, even without a neutral connection.
Conventional attempts to provide lighting control products for wall switch control without a neutral connection are available, but limited in operation. One conventional approach is based on a wall switch module simulating a load, wherein the load changes depend on the status of the connected load. For example, when a lighting fixture is off, the wall switch internal loading may become very high resulting in increased power consumption at the wall switch internal load which causes the lighting fixture to be off. However, if the lighting fixture is turned on, the wall switch internal load may decrease and result in enough power to turn on the fixture. One major limitation with this approach is that the actual connected load must be incandescent loading, such as a tungsten light bulb. This conventional method will not work with compact fluorescent lamps (CFL) or fluorescent light. CFL exhibit very high impedance requiring higher levels of operating current than incandescent lamps. Conventional wall switch control devices and methods without a neutral connection do not provide enough current to operate CFL. Further, CFL typically requires less energy than traditional tungsten bulbs. In addition, some countries have proposed rules that with ban tungsten bulbs from the marketplace in the near future. Therefore, there is a need for a wall switch control module that overcomes one or more of the aforementioned drawbacks.